It's probably just a ingrown hair, pimple, or a heat bump. You have nothing to worry about, it should go away within a few days.
Make sure that when you shower and bathe that area, that you only use plain clear water or washes made specifically for the geinital area. Body washes, bubble bath, and shampoos can all mess up the vaginal pH.
Try washing gently with clear, warm water only for the next week or so and see if you notice a difference for the better, if not You should probably check in with your Dr.